From 3666f4d118c2bf4472c5eedeacd72bb7c5b2a646 Mon Sep 17 00:00:00 2001
From: Liu Liu <i@liuliu.me>
Date: Mon, 4 Oct 2021 22:52:59 -0400
Subject: [PATCH] Add keys method in WorkspaceDictionary

---
 docs/reference/Workspace.md                | 33 ++++++++++++++++++++++
 sourcedocs.sh                              |  2 +-
 src/Workspace.swift                        |  5 ++++
 src/sqlite/SQLiteWorkspaceDictionary.swift | 12 ++++++++
 src/tests/DictionaryTests.swift            | 10 +++++++
 5 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/docs/reference/Workspace.md b/docs/reference/Workspace.md
index 42d1f7f0e..4a067e69e 100644
--- a/docs/reference/Workspace.md
+++ b/docs/reference/Workspace.md
@@ -24,6 +24,39 @@ func fetchWithinASnapshot<T>(_: () -> T) -> T
 Provide a consistent view for fetching multiple objects at once.
 
 
+**PROTOCOL**
+
+# `WorkspaceDictionary`
+
+```swift
+public protocol WorkspaceDictionary
+```
+
+## Properties
+### `keys`
+
+```swift
+var keys: [String]
+```
+
+Return all keys available in the dictionary. This is an expensive (for this dictionary)
+method as it fetches from disk, from in-memory structures, and acquire locks if needed.
+
+## Methods
+### `synchronize()`
+
+```swift
+func synchronize()
+```
+
+Force current thread to wait until everything has been written to disk.
+Note that this function forces wait to disk, but not synchronize across
+threads. You could have one thread called synchronize while another thread
+is still holding their own lock to update in-memory value. It doesn't guarantee
+the first thread will wait the second thread's dictionary[key] = value to finish.
+This method only guarantees all writes on current thread done.
+
+
 **PROTOCOL**
 
 # `Workspace`
diff --git a/sourcedocs.sh b/sourcedocs.sh
index bc4de7321..92f01042b 100755
--- a/sourcedocs.sh
+++ b/sourcedocs.sh
@@ -3,6 +3,6 @@
 sourcedocs generate --spm-module Dflat
 sourcedocs generate --spm-module SQLiteDflat
 
-(cat Documentation/Reference/protocols/Queryable.md ; echo -e "\n" ; cat Documentation/Reference/protocols/Workspace.md ; echo -e "\n" ; cat Documentation/Reference/classes/QueryBuilder.md ; echo -e "\n" ; cat Documentation/Reference/protocols/WorkspaceSubscription.md ; echo -e "\n" ; cat Documentation/Reference/enums/SubscribedObject.md ; echo -e "\n" ; cat Documentation/Reference/classes/QueryPublisherBuilder.md) > docs/reference/Workspace.md
+(cat Documentation/Reference/protocols/Queryable.md ; echo -e "\n" ; cat Documentation/Reference/protocols/WorkspaceDictionary.md ; echo -e "\n" ; cat Documentation/Reference/protocols/Workspace.md ; echo -e "\n" ; cat Documentation/Reference/classes/QueryBuilder.md ; echo -e "\n" ; cat Documentation/Reference/protocols/WorkspaceSubscription.md ; echo -e "\n" ; cat Documentation/Reference/enums/SubscribedObject.md ; echo -e "\n" ; cat Documentation/Reference/classes/QueryPublisherBuilder.md) > docs/reference/Workspace.md
 (cat Documentation/Reference/protocols/TransactionContext.md ; echo -e "\n" ; cat Documentation/Reference/extensions/TransactionContext.md ; echo -e "\n" ; cat Documentation/Reference/enums/TransactionError.md) > docs/reference/TransactionContext.md
 (cat Documentation/Reference/classes/SQLiteWorkspace.md ; echo -e "\n" ; cat Documentation/Reference/enums/SQLiteWorkspace.FileProtectionLevel.md ; echo -e "\n" ; cat Documentation/Reference/enums/SQLiteWorkspace.WriteConcurrency.md ; echo -e "\n" ; cat Documentation/Reference/enums/SQLiteWorkspace.Synchronous.md) > docs/reference/SQLiteWorkspace.md
diff --git a/src/Workspace.swift b/src/Workspace.swift
index 47d78ef66..055f56a9b 100644
--- a/src/Workspace.swift
+++ b/src/Workspace.swift
@@ -52,6 +52,11 @@ public protocol WorkspaceDictionary {
    * This method only guarantees all writes on current thread done.
    */
   func synchronize()
+  /**
+   * Return all keys available in the dictionary. This is an expensive (for this dictionary)
+   * method as it fetches from disk, from in-memory structures, and acquire locks if needed.
+   */
+  var keys: [String] { get }
 }
 
 public protocol Workspace: Queryable {
diff --git a/src/sqlite/SQLiteWorkspaceDictionary.swift b/src/sqlite/SQLiteWorkspaceDictionary.swift
index f1cc06be5..c559edea2 100644
--- a/src/sqlite/SQLiteWorkspaceDictionary.swift
+++ b/src/sqlite/SQLiteWorkspaceDictionary.swift
@@ -451,6 +451,7 @@ struct SQLiteWorkspaceDictionary: WorkspaceDictionary {
       storage.unlock(hashValue)
     }
   }
+
   func synchronize() {
     let group = DispatchGroup()
     group.enter()
@@ -461,6 +462,17 @@ struct SQLiteWorkspaceDictionary: WorkspaceDictionary {
       })
     group.wait()
   }
+
+  var keys: [String] {
+    let items = workspace.fetch(for: DictItem.self).where(DictItem.namespace == storage.namespace)
+    var keys = Set(items.map { $0.key })
+    for i in 0..<Storage.size {
+      storage.lock(i)
+      defer { storage.unlock(i) }
+      keys.formUnion(storage.dictionaries[i].keys)
+    }
+    return Array(keys)
+  }
 }
 
 extension SQLiteWorkspaceDictionary.Storage {
diff --git a/src/tests/DictionaryTests.swift b/src/tests/DictionaryTests.swift
index 1951690fb..bd2e9f89a 100644
--- a/src/tests/DictionaryTests.swift
+++ b/src/tests/DictionaryTests.swift
@@ -172,6 +172,15 @@ class DictionaryTests: XCTestCase {
     XCTAssertEqual(anotherDict["stringValue", default: "1234"], "1234")
   }
 
+  func testIterateKeys() {
+    guard var dictionary = dflat?.dictionary else { return }
+    dictionary["stringValue"] = "abcde"
+    dictionary["intValue"] = Int(10)
+    dictionary["doubleValue"] = Double(12.3)
+    let keys = dictionary.keys
+    XCTAssertEqual(Set(keys), Set(["stringValue", "intValue", "doubleValue"]))
+  }
+
   static let allTests = [
     ("testReadWriteReadCodableObject", testReadWriteReadCodableObject),
     ("testReadWriteReadFlatBuffersObject", testReadWriteReadFlatBuffersObject),
@@ -185,5 +194,6 @@ class DictionaryTests: XCTestCase {
     ("testReadWriteReadFloat", testReadWriteReadFloat),
     ("testReadWriteReadDouble", testReadWriteReadDouble),
     ("testReadWriteReadString", testReadWriteReadString),
+    ("testIterateKeys", testIterateKeys),
   ]
 }